PHILADELPHIA (CBS) — There’s a disturbing new trend with fatal-drug related crashes now outpacing deadly accidents involving alcohol. With a growing number of states legalizing marijuana, combined with the opioid epidemic, experts say there’s been a significant jump in the percentage of drivers killed while on drugs.

According to a new report, in 2016, alcohol was involved in 38 percent of driver deaths, while 44 percent of drivers killed tested positive for drugs – a jump from just 28 percent in 2006.

More than half of the drivers had marijuana, opioids or a combination of the two in their system.

“We definitely see states liberalizing marijuana laws. There are more prescriptions of drugs than ever before and we are in the midst of an opioid crisis,” said Russ Martin, director of government relations for the Governor’s Highway Safety Association.

Credit: (CBS3)

Experts say identifying and testing a driver for drugs can be difficult.

Police say a woman on sedatives and painkillers caused a deadly accident after the driver was reportedly in a fender bender just 19 minutes prior, but the officer let her go because he didn’t see any signs of impairment.

“Right now, we don’t have a nationally agreed upon way to test drivers for drug impairment similar to a breathalyzer or blood test for alcohol,” said Martin.

Ron Edwards was riding his motorcycle when a driver ran a red light and killed him. Police say the driver of the car had marijuana in his system.

Many police departments are now training officers to better recognize drivers who are high in an effort to prevent more deaths on the road.

In Pennsylvania, there’s been a drop in drunk driving arrests, but an increase in those involving drugs. More than 20,000 charges for driving under the influence of an impairing drug were filed last year.